Upon completing work for his bachelor’s degree at the age of twenty, John Bolton left the University of Cambridge in his native England to serve in the Royal Navy during World War II. After the war, he stayed in Australia to develop radio astronomy for the Commonwealth Scientific and Industrial Research Organization. With an ingenious interferometer using reflection from the sea as one element, his team achieved sufficient angular resolution to identify the first known radio sources, Taurus A, Centaurus A, and Virgo A, as the Crab Nebula and the galaxies NGC 5128 and M 87. Later they located Sagittarius A, the galactic center. They also made an important discovery relating a solar flare to the aurora. After a brief period working in cloud physics in Australia, Bolton built Caltech’s Owens Valley Radio Observatory and directed it from 1955-60. He then returned to Australia to supervise the completion and become the first director of the Australian National Radio Astronomy Observatory at Parkes. There he supervised necessary modifications of the instruments and relayed the television signals from the first lunar landing in 1969. His southern sky surveys—the Parkes Catalogue listed more than 8000 radio sources—led to the discovery of many quasars and greatly increased interaction between optical and radio astronomers. He also made many optical observations at observatories in California to identify his radio sources. His students became leaders in radio astronomy in the United States and the United Kingdom as well as Australia.